Can't provide much info with just a serial number - what county is indicated as the place of manufacture?
Does it say "made under license of" Carl Walther? If so, it's US made, as most .380 PPKs in this country were.
If it is German made, it should say either "Zella-Methis" or "Ulm Do" as the city of manufacture. If it says "Zella-Methis", it's pre-war. The factory was moved to Ulm in the 1950s.
If it says "Made in France" it was made during the years that Walther operated at the Manhurin plant, just across the border in France, right after the war. Manhurin PPKs are really, really rare in the US.
Is it blued or stainless?
Ken Strayhorn
Hillsborough NC